Severe Chronic Neutropenia International Registry Research Articles

HAX1-related congenital neutropenia: Long-term observation in paediatric and adult patients enrolled in the European branch of the Severe Chronic Neutropenia International Registry (SCNIR).

HAX1-related congenital neutropenia (HAX1-CN) is a rare autosomal recessive disorder caused by pathogenic variants in the HAX1 gene. HAX1-CN patients suffer from bone marrow failure as assessed by a maturation arrest of the myelopoiesis revealing persistent severe neutropenia from birth. The disorder is strongly associated with severe bacterial infections and a high risk of developing myelodysplastic syndrome or acute myeloid leukaemia. This study aimed to describe the long-term course of the disease, the treatment, outcome and quality of life in patients with homozygous HAX1 mutations reported to the European branch of the Severe Chronic Neutropenia International Registry. We have analysed a total of 72 patients with different types of homozygous (n = 68), compound heterozygous (n = 3), and digenic (n = 1) HAX1 mutations. The cohort includes 56 paediatric (<18 years) and 16 adult patients. All patients were initially treated with G-CSF with a sufficient increase in absolute neutrophil counts. Twelve patients required haematopoietic stem cell transplantation for leukaemia (n = 8) and non-leukaemic indications (n = 4). While previous genotype-phenotype reports documented a striking correlation between two main transcript variants and clinical neurological phenotypes, our current analysis reveals novel mutation subtypes and clinical overlaps between all genotypes including severe secondary manifestations, e.g., high incidence of secondary ovarian insufficiency.

Outcomes for patients with severe chronic neutropenia treated with granulocyte colony-stimulating factor

AbstractSevere chronic neutropenia (SCN), defined as blood neutrophils <0.5 × 109/L for >3 months, is an uncommon hematological condition associated with recurrent and severe bacterial infections. After short-term clinical trials showed the benefits of granulocyte colony-stimulating factor (G-CSF) treatment for SCN, SCNIR (Severe Chronic Neutropenia International Registry) opened to determine the long-term benefits and safety of this treatment. This report summarizes findings from more than 16 000 patient-years of prospective observations for patients with congenital and acquired SCN. We observed that adverse outcomes depend on the underlying etiology. Myelodysplasia (MDS) and acute myeloid leukemia (AML) occur infrequently and largely in patients with congenital neutropenias. Having cyclic or chronic autoimmune/ idiopathic neutropenia portends a favorable prognosis. A few patients with idiopathic neutropenia evolve to develop lymphoid malignancies, but they do not appear to be at increased risk of myeloid malignancies, even with very long-term G-CSF therapy. Progression to systemic autoimmune diseases, bone marrow (BM) failure, aplastic anemia, or nonmyeloid malignancies are not expected consequences of SCN or treatment with G-CSF.

Spectrum of Pathogenic Genetic Variants in a Large Cohort of North American Congenital and Cyclic Neutropenia Patients: A Report from the Severe Chronic Neutropenia International Registry

▪Severe congenital neutropenia (SCN) is characterized by persistent neutropenia and risk of invasive, life-threatening infection as well as transformation to hematopoietic malignancy. The closely related syndrome cyclic neutropenia is characterized by recurrent episodic neutropenia accompanied by symptoms including infection. Understanding the genetic etiology of congenital neutropenia can help to direct therapy, guide surveillance and health maintenance strategies, and contribute to our understanding of basic neutrophil biology. Although mutations in ELANE are the most frequent cause of congenital neutropenia, there is a wide and ever-growing list of additional causative variants. Additionally, there appears to be regional genetic variability. For example, mutations in HAX1 are rarely if ever observed in North America while they are more common in Europe. We undertook exome sequencing of a large cohort from the Severe Chronic Neutropenia International Registry (SCNIR) of North America in an effort to define the genetic spectrum of congenital neutropenia and aid in the discovery of new pathogenic variants.We expanded our previously reported study of whole exome sequencing to include 152 cases of chronic neutropenia, comprised of 94 cases of SCN and 58 cases of cyclic neutropenia. We selected cases in which ELANE testing was negative, or in a small minority of cases, where ELANE testing had not yet been performed. Indeed, exome sequencing only identified 7 cases (5 SCN and 2 cyclic) carrying pathogenic ELANE mutations in this cohort. In the remaining 145 cases, we analyzed exomes for the presence of variants in genes previously associated with congenital neutropenia including AK2, AP3B1, CD40LG, CLPB, CSF3R, CXCR2, CXCR4, DNAJC21, DNM2, DOCK2, EFL1, EIF2AK3, ELANE, G6PC3, GATA1, GATA2, GFI1, GINS1, HAX1, IRAK4, JAGN1, KAT6A, KRAS, LAMTOR2, LYST, MYD88, PGM3, PSTPIP1, RAB27A, RAC2, SBDS, SEC61A1, SLC37A4, SMARCD2, SRP54, STK4, TAZ, TCIRG1, TCN2, TLR8, USB1, VPS13B, VPS45, WAS, WDR1 and WIPF1. Pathogenic heterozygous mutations of CLPB that localize to the ATP-binding pocket were identified in 7 cases, making it the second most common cause of congenital neutropenia in North America. We additionally identified 4 cases with G6PC3 pathogenic variants, and one case each with pathogenic variants in JAGN1, CXCR4 (the cause of WHIM syndrome), germline homozygous CSF3R, and GFI1.Interestingly, we identify 2 unrelated individuals (one with SCN and one with cyclic) and 2 siblings with SCN all of whom possess a recently described heterozygous variant in SRP54 (p.T117del). We collected genomic DNA from the affected mother of the 2 siblings, an additional unaffected sibling, and the unaffected grandparents. Through this kinship, we can confirm the de novo appearance of this variant in the second generation and demonstrate that it tracks with disease status (Figure 1). We also identified 2 unrelated individuals with SRP54 variants affecting residue 175 also located within the GTPase domain (p.G175E or p.G175del). Both variants are absent from the gnomAD database, and studies are underway to demonstrate de novo acquisition.In summary, we have defined the spectrum of mutations present in ELANE-wildtype chronic neutropenia cases in North America. Pathogenic or likely pathogenic variants were identified in 26 out of 145 (18%) cases. The most frequently mutated genes were of CLPB, SRP54, and G6PC3, while mutations in HAX1 were not seen. Importantly, some of these mutations are associated with genetic syndromes with extra-hematopoietic findings (for example, CLPB and SRP54) that would warrant additional evaluations and targeted health maintenance. These findings emphasize the importance of sending large panels for genotyping, rather than targeted ELANE testing. [Display omitted] DisclosuresBolyard: X4 Pharmaceuticals: Research Funding. Makaryan: Emendo Biotherapeutic: Research Funding. Dale: X4 Pharmaceuticals: Consultancy, Honoraria, Research Funding.

Cyclic Neutropenia, Congenital and Idiopathic Neutropenia

Background: Cyclic neutropenia (CyN) is an autosomal dominant disease usually attributable to mutations in the gene for neutrophil elastase, ELANE . The diagnosis depends upon serial blood counts (at the minimum every other day or three days a week for 6 weeks) showing periods of severe neutropenia (absolute neutrophil count [ANC] < 0.2 x 109/L) recurring at approximately 21 day intervals. The diagnosis can be confirmed by Lomb periodogram analysis. Genetic testing is helpful but not diagnostic because of the overlap of the mutational patterns in ELANE for CyN and severe congenital neutropenia (SCN).Methods: We reviewed clinical and laboratory data for 87 patients enrolled in the Severe Chronic Neutropenia International Registry (SCNIR) with a diagnosis of CyN in 41 kindreds. Their family histories indicated that there were 117 other neutropenic family members. For this review we focused on 53 CyN patients in 15 kindreds who met the following criteria: two or more patients within the kindred had 10 or more CBCs available for analysis. Using data collected before treatment with G-CSF by the patients' primary physicians, we examined graphically displayed serial ANC's for each affected family member and performed periodogram analysis. We compared patterns of ANC fluctuations within families and for patients of similar ages within these families.Findings and implications: •Within families, if 1 patient has a mutation in ELANE, all other neutropenic members will have the same mutation in ELANE.•Within families if the index case has typical and diagnostic oscillations in blood neutrophils, other affected family members often have neutropenia without clear or diagnostic oscillations in their counts. If the patient has a mutation in ELANE, the diagnosis of SCN is sometimes assigned.•In familial CyN the oscillations tend to dampen with lower peaks and somewhat less severe neutropenia in older adults (> 30 years of age). Unless these patients have genetic testing showing a mutation in ELANE or another gene associated with neutropenia, they may be given the diagnosis of chronic idiopathic neutropenia.•The Lomb periodogram is very useful for diagnosing CyN. It is a web-based tool readily accessible on the SCNIR web site, https://depts.washington.edu/registry/. However, it is necessary to collect sufficient number of counts (usually at least 20 counts spaced at regular intervals) to use this method to make the diagnosis of CyN. Although visually there was cycling in at least one member of the 15 families, only 5 families had a member who had CyN with a 95 or 99 percent confidence level based on the Lomb periodogram.Conclusions:Careful family history and serial measurements of ANCs are the foundations for the diagnosis of CyN. Genetic sequencing and identification of specific mutations in ELANE are helpful for prognosis. The Lomb periodogram is helpful, but requires a robust series of counts to assure that cycling is present with a high (95%) confidence level. DisclosuresDale:Genzyme (now owned by Sanofi-Aventis): Consultancy, Patents & Royalties, Research Funding; Genkyotex: Other: DSMB (work completed 6/2015); Hospira: Consultancy; Prolong: Consultancy; Boheringer-Ingelheim: Consultancy; Coherus: Consultancy; Omeros: Other: DSMB; Shire: Other: Independent Review Board; X4Pharma: Research Funding; Philips: Research Funding; Wolter Kluwer: Other: Editor, Current Opinions in Hematology; WedMD/Medscape: Membership on an entity's Board of Directors or advisory committees; National Institutes of Health: Research Funding; University of Washington: Employment, Research Funding; American College of Physicians: Other: Editor and author; GlaxoSmithKline: Equity Ownership; Johnson&Johnson: Equity Ownership; Cellerant: Membership on an entity's Board of Directors or advisory committees; Sanofi Aventis: Consultancy, Editor, Current Opinions in Hematology, Honoraria; Amgen: Consultancy, Research Funding.

Nicotinamide (vitamin B3) treatment improves response to G‐CSF in severe congenital neutropenia patients

Nicotinamide (vitamin B3) treatment improves response to G‐CSF in severe congenital neutropenia patients

Myelodysplasia syndrome and acute myeloid leukemia in patients with congenital neutropenia receiving G-CSF therapy

AbstractGranulocyte colony-stimulating factor (G-CSF) has had a major impact on management of “severe chronic neutropenia,” a collective term referring to congenital, idiopathic, or cyclic neutropenia. Almost all patients respond to G-CSF with increased neutrophils, reduced infections, and improved survival. Some responders with congenital neutropenia have developed myelodysplastic syndrome and acute myeloblastic leukemia (MDS/AML), which raises the question of the role of G-CSF in pathogenesis. The Severe Chronic Neutropenia International Registry (SCNIR), Seattle, WA, has data on 696 neutropenic patients, including 352 patients with congenital neutropenia, treated with G-CSF from 1987 to present. Treatment and patient demographic data were analyzed. The 352 congenital patients were observed for a mean of 6 years (range, 0.1-11 years) while being treated. Of these patients, 31 developed MDS/AML, for a crude rate of malignant transformation of nearly 9%. None of the 344 patients with idiopathic or cyclic neutropenia developed MDS/AML. Transformation was associated with acquired marrow cytogenetic clonal changes: 18 patients developed a partial or complete loss of chromosome 7, and 9 patients manifested abnormalities of chromosome 21 (usually trisomy 21). For each yearly treatment interval, the annual rate of MDS/AML development was less than 2%. No significant relationships between age at onset of MDS/AML and patient gender, G-CSF dose, or treatment duration were found (P > .15). In addition to the 31 patients who developed MDS/AML, the SCNIR also has data on 9 additional neutropenic patients whose bone marrow studies show cytogenetic clonal changes but the patients are without transformation to MDS/AML. Although our data does not support a cause-and-effect relationship between development of MDS/AML and G-CSF therapy or other patient demographics, we cannot exclude a direct contribution of G-CSF in the pathogenesis of MDS/AML. This issue is unclear because MDS/AML was not seen in cyclic or idiopathic neutropenia. Improved survival of congenital neutropenia patients receiving G-CSF therapy may allow time for the expression of the leukemic predisposition that characterizes the natural history of these disorders. However, other factors related to G-CSF may also be operative in the setting of congenital neutropenia.

Stem cell transplantation in patients with severe congenital neutropenia without evidence of leukemic transformation.

Severe congenital neutropenia (CN) (Kostmann syndrome) is a hematologic disorder characterized by a maturation arrest of myelopoiesis at the promyelocyte/myelocyte stage of development. This arrest results in severe neutropenia leading to absolute neutrophil counts (ANC) below 0.2 x 10(9)/L associated with severe bacterial infections from early infancy. Data on over 300 patients with CN collected by the Severe Chronic Neutropenia International Registry (SCNIR) beginning in 1994 indicate that more than 90% of these patients respond to recombinant human granulocyte-colony stimulating factor (r-HuG-CSF) treatment with an ANC greater than 1. 0 x 10(9)/L. For patients who are refractory to r-HuG-CSF treatment and continue to have severe and often life-threatening bacterial infections, hematopoietic stem cell transplantation is the only currently available treatment. We report on a total of 11 patients with CN reported to the SCNIR who underwent transplantation for reasons other than malignant transformation between 1976 and 1998. Of these patients, 8 were nonresponders or showed only partial response to r-HuG-CSF treatment with ongoing infections. Results from these patients suggest that transplantation of stem cells from an HLA-identical sibling is beneficial for patients refractory to r-HuG-CSF. (Blood. 2000;95:1195-1198)

Registries for study of nonmalignant hematological diseases: the example of the Severe Chronic Neutropenia International Registry.

Registries provide 'real world' perspectives on the natural history and outcomes for many clinical conditions. The purpose of this review is to identify registries for nonmalignant hematological disease and to describe the operation of a successful long-term registry for patients with severe chronic neutropenia. There was an upswing in registries about 20 years ago, based on optimism about their utility to improve patient care. To show value, registries must define outcomes for populations of patients with specific medical conditions and the effects of treatment. This is challenging for many reasons. The Severe Chronic Neutropenia International Registry is an example of a successful registry. This report describes underlying reasons for its success. Registries are important to organize and analyze clinical information across geographic, ethnic and social boundaries. They are also challenging to organize, administer and support.

Family studies of warts, hypogammaglobulinemia, immunodeficiency, myelokathexis syndrome.

WHIM syndrome (warts, hypogammaglobulinemia, immunodeficiency, myelokathexis, or WHIMs) is a very rare autosomal dominant immunodeficiency disorder attributable to mutations in CXCR4. We reviewed clinical manifestations in 24 patients in 9 families to expand understanding of this syndrome. Warts, cellulitis and respiratory infections are common in patients with WHIMs. Less commonly these patients have congenital heart disease, human papilloma virus-associated malignancies (cervical and vulvular) and lymphomas. Hearing loss because of recurrent otitis media is another important complication. Treatment with granulocyte colony-stimulating factor is controversial; this review indicates that it is effective to prevent and treat infections based upon long-term observations of patients enrolled in the Severe Chronic Neutropenia International Registry. Understanding the natural history and diversity of this syndrome are important for ongoing clinical trials of novel agents to treat WHIMs. WHIM syndrome has diverse manifestations; some features occur consistently in almost all patients, for example, neutropenia, lymphocytopenia and mild hypogammaglobulinemia. However, the clinical consequences are quite variable across patient cohorts and within families. Each complication is important as a cause for morbidity and a source for patient and family concerns.

Editorial introductions

Current Opinion in Hematology was launched in 1994. It is part of a successful series of review journals whose unique format is designed to provide a systematic and critical assessment of the literature as presented in the many primary journals. The field of hematology is divided into nine sections that are reviewed once a year. Each section is assigned a Section Editor, a leading authority in the area, who identifies the most important topics at that time. Here we are pleased to introduce the Editor and the Section Editor for this issue. EDITOR IN CHIEF Narla MohandasNarla MohandasDr Narla Mohandas is Vice President for Research at New York Blood Center, New York, USA. He received his doctoral degree from Washington University, St. Louis, USA in Chemical Engineering. After completing post-doctoral training in hematology research with Dr Marcel Bessis, Institute of Cellular Pathology in Paris, France, he joined the Faculty of Laboratory Medicine at University of California, San Francisco where he spent 13 years. In 1989, he moved to Lawrence Berkeley National Laboratory, University of California to head the Hematopoiesis group. During his 12-year tenure at the Berkeley Laboratory he also served as Interim Director of Human Genome Project for three years. In 2001, he moved to the New York Blood Center. Dr Mohandas’ scientific interests during his 45-year research career have focused on red cell physiology and pathology. In particular, his efforts have contributed to improved understanding of the molecular and structural basis for red cell membrane disorders, developing detailed mechanistic insights into pathophysiology of thalassemias and sickle cell disease, characterizing structural and functional changes induced in red cells by the malarial parasite, plasmodium falciparum. His research efforts during last ten years are focused on molecular understanding of normal and disordered human erythropoiesis including Diamond-Blackfan anemia and Myelodysplasia. Dr Mohandas served as a member of the National Institutes of Health Hematology study section for 18 years and is currently member of the NHLBI Advisory Council. He has been a member of numerous committees including the Executive committee of American Society of Hematology. He served as Associate Editor of Blood from 2003–2012 and is currently Editor-in-Chief of Blood Cells, Molecules and Disease and of Current Opinion in Hematology. SECTION EDITOR David C. DaleDavid C. DaleDr David C. Dale is Professor of Medicine and former Dean of the School of Medicine at the University of Washington. He is a native of Knoxville, Tennessee, and a graduate of the Harvard Medical School. He received post-graduate training at Massachusetts General Hospital, the National Institutes of Health and the University of Washington. He has career-long interests in medical education, medical history and basic and clinical research focused on inflammation, neutrophils, and the clinical problem of neutropenia. Dr Dale has served as President of the American College of Physicians, the Society of General Internal Medicine, the Western Association of Physicians, the Medical Honor Society-Alpha Omega Alpha, and the American Clinical and Climatological Association. He is Editor-in-Chief Emeritus for the Scientific American Medicine the medicine text also known as ACP Medicine. He is the Founder and Co-Director of the Severe Chronic Neutropenia International Registry and Co-President (with Rose Marie Dale) of the Friends of the University of Washington School of Medicine. Dr Dale is actively involved in teaching, research and patient care at the University of Washington and a member of the Council for the Washington Chapter of ACP.

Severe Chronic Neutropenia in the Large Granular Lymphocyte Syndrome: Outcomes in Response to Granulocyte Colony Stimulating Factor (G-CSF) and Immunosuppressive Therapies

The large granular lymphocyte (LGL) syndrome and large granular lymphocytic leukemia (LGLL) are rare hematological disorders. Through the Severe Chronic Neutropenia International Registry (SCNIR) we have followed the clinical course and treatment responses of 27 LGL patients presenting with severe chronic neutropenia without evidence of leukemia, rheumatoid arthritis or autoimmune diseases. This report focuses on their treatment responses to G-CSF and outcomes with and without other immunosuppressive therapies. Methods: Patients with severe chronic neutropenia and a diagnosis of LGL syndrome (at least 3 ANC values &amp;lt; 0.5 x 109/L over a 3 month period) were enrollment in the SCNIR if they do not have concomitant systemic autoimmune disease, myeloid or lymphoid malignancy or drug-induced neutropenia. Findings: The 27 LGL patients (8 males, median age 53; 19 females, median age 57) had chronic neutropenia for approximately 4 years (range 0.4 - 25.6 years) before enrollment. Diagnoses were primarily based on FACS analysis (12 bone marrow [50%]; 11 blood and bone marrow [46%]; 1 blood only [4%]). None of these patients presented with lymphocytosis, i.e., ALC &amp;gt; 5.0 x 109/L. Before enrollment, 7 patients had anti-neutrophil antibody tests (3 positive, 4 negative), 4 patients had antinuclear antibody tests (2 positive, 2 negative), and ANCA was positive for the one patient tested. After enrollment, additional results were: 1 patient had a negative anti-neutrophil antibody, 8 patients had antinuclear antibody tests (2 positive, 6 negative), and ANCA was positive in two additional patients. The diagnosis of LGL was based on increased LGL cells in the blood or bone marrow, most frequently increased CD 3+, CD 8+, CD 57+ cells. Increases in lymphocytes in the marrow, often in clusters were a common finding; lymphocytes in the marrow ranged from 6-79%. The range of CD 57+ in blood 11-19%, bone marrow 19-61%; CD 56+/NK cells in blood 0.06-14%, bone marrow &amp;lt;1-76.8%; increased CD 8+/CD 3+ in blood 1.5-90%, bone marrow &amp;lt;1-91%. Ten patients have gene rearrangement studies, 7 prior to enrollment (3 negative, 4 positive) and 3 patients had these studies after enrollment, all positive. Because most patients had neutropenia, fevers and infections we evaluated the effectiveness and safety of G-CSF therapy. Treatments were G-CSF alone (13), G-CSF with prednisone (5), G-CSF with methotrexate and prednisone (4), G-CSF with methotrexate alone (2), G-CSF with cyclosporine (1), G-CSF with cyclosporine and prednisone (1), and G-CSF with prednisone, methotrexate and cyclosporine (1). Prior to G-CSF treatment the median ANC was 0.54 x 109/L, mean 1.48 +/- 0.35 SEM. The ALC median was 1.67 x 109/L, mean 2.74 +/- 0.74. The G-CSF dosing median was 1.44 mcg/kg/day, mean 2.27 +/- 0.31. All responded to G-CSF alone or in combination therapy to achieve a mean ANC greater than 1.0 x 109/L. After G-CSF treatment the median ANC was 2.23 x 109/L, mean 3.78 +/- 0.40. The ALC median was 2.24 x 109/L, mean 3.17 +/- 0.48. Time period for SCNIR observation median years is 9.6 years; mean 10.0 +/- 1.2, range 0.4 to 23.1 years. There was a total 270 years of observation in the SCNIR and 307 years of G-CSF administration in this group of 27 patients. The increase in neutrophils was consistently associated with fewer episodes of fever, infections and antibiotic use. One of 27 patients had episodic thrombocytopenia (&amp;lt;50 x 109/L) before G-CSF and continued while on G-CSF. Seven of 26 patients reported episodic thrombocytopenia after starting G-CSF. There were no report episodes of significant bleeding. Fourteen of 27 are now living, ages 17 to 72, and all have continued on treatment. Over the 24 year observation period, 5 patients developed Hodgkin disease (1) or non-Hodgkin lymphoma (5); and 5/6 died. Five other LGL patients died of sepsis or pneumonia. Other deaths were attributed to a T-cell lymphoproliferative disorder (1), chronic pancreatitis (1) and lung cancer (1). There were no myeloid malignancies. Conclusions: Our long term observations suggests that the combination of low dose G-CSF plus methotrexate or cyclosporine appears to be more effective than either drug alone, titrated each to minimal effective doses, and continued indefinitely. There was no increased frequency of opportunistic infections. The expected course is a long period of normal ANCs without other autoimmune diseases. Evolution to lymphoid, not myeloid, malignancies is the greatest concern. Disclosures Dale: Coherus: Consultancy; x4pharma: Consultancy, Honoraria, Research Funding; Athelas: Equity Ownership; Prolong: Consultancy; Cellerant: Other: Scientific Advisory Board; Hospira: Consultancy; Amgen: Consultancy, Research Funding; Sanofi Aventis: Consultancy, Honoraria; Beheringer/Ingelheim: Consultancy. Newburger:TransCytos LLC: Consultancy; X4 Pharmaceuticals: Consultancy, Honoraria.

Heterozygous Mutations of Clpb As a Newly Identified and Frequent Cause of Severe Congenital Neutropenia

Severe congenital neutropenia (SCN) is an inborn disorder of granulopoiesis characterized by severe chronic neutropenia from birth, premature death secondary to infectious complications, and transformation to myeloid malignancy. Although many cases of SCN are associated with mutations in ELANE, encoding the neutrophil elastase, roughly one-third of cases do not have an identifiable genetic cause. In collaboration with the Severe Chronic Neutropenia International Registry (SCNIR), we performed exome sequencing on 90 cases of congenital neutropenia. Heterozygous missense mutations of CLPB were identified in six patients with SCN. None of these patients had mutations in other genes known to cause SCN. A total of 5 different mutations were identified that clustered within the ATPase domain. Of note, all of these mutations were predicted to be functionally deleterious and had a frequency of &amp;lt;0.002% in the ExAC and gnomAD databases. We subsequently identified heterozygous CLPB mutations in an additional 3 cases of SCN that were not part of our original cohort. Prior studies showed that biallelic mutations of CLPB are associated with a syndrome defined by 3-methylglutaconic aciduria (3-MGA), cataracts, neurologic disease, and variable neutropenia. In our original cohort of 6 SCN patients with heterozygous CLPB mutations, 3-MGA was not present in the three cases where urine samples were available and none had reported cataracts. In total, 3 had neurologic abnormalities (2 seizures and 1 developmental delay). Of note, the CLPB mutations present in syndromic cases were distinct from those seen in our SCN cohort, and none of the mutations in our series are biallelic. CLPB encodes for caseinolytic peptidase B, a protein implicated in protein folding in bacteria and yeast but with an unknown role in human granulopoiesis. Based on these observations, we hypothesize that CLPB is required for normal basal granulopoiesis and that the heterozygous CLPB mutations identified in our study act in a dominant-negative fashion to disrupt granulopoiesis. To test this hypothesis, two complementary genetic approaches were employed. First, we used CRISPR-Cas9 gene editing to generate null mutations in CLPB in human cord blood-derived CD34+ hematopoietic stem/progenitor cells (HSPCs). Using this approach, we are able to achieve greater than 90% editing efficiency as assessed by next generation sequencing. The genetically modified HSPCs were cultured for 14 days under conditions that promote granulocytic differentiation. Modified HSPCs were also seeded into methylcellulose cultures to measure CFU-G. The percentage and absolute number of mature granulocytes, but not early granulocytic precursors (promyelocytes and myelocytes), were significantly reduced in cultures of gene-edited cord blood CD34+ cells. Moreover, the frequency of edited cells decreases over time in our culture system indicating that CLPB-knockout cells have a competitive disadvantage. A significant decrease in CFU-G also was observed. Second, we generated lentivirus expressing all 5 of the neutropenia-associated heterozygous CLPB mutations identified in our SCN cohort (N496K, E557K, R561G, R603H, and R620C). Expression of all of these mutants (except R603H) in cord blood-derived CD34+ cells was associated with a significant decrease in mature neutrophils and corresponding increase in early granulocytic precursors. These four CLPB mutants also resulted in a decrease in CFU-G. Collectively, these data strongly suggest that heterozygous mutations of CLPB are a new cause of congenital neutropenia. Indeed, in the North American population, CLPB mutations appear to be the second most common cause of congenital neutropenia, behind ELANE mutations. Studies are underway to examine the molecular mechanisms by which mutant CLPB disrupts granulopoiesis. Disclosures Dale: Coherus: Consultancy; Beheringer/Ingelheim: Consultancy; Athelas: Equity Ownership; Amgen: Consultancy, Research Funding; Sanofi Aventis: Consultancy, Honoraria; Cellerant: Other: Scientific Advisory Board; Hospira: Consultancy; Prolong: Consultancy; x4pharma: Consultancy, Honoraria, Research Funding.

Family Studies of Whim Syndrome

Background: WHIM syndrome (warts, hypogammaglobulinemia, immunodeficiency, myelokathexis) is a very rare autosomal dominant immunodeficiency disorder attributable to mutations in CXCR4. Neutropenia, lymphocytopenia and monocytopenia occur because the CXCR4 mutation impairs normal leukocyte trafficking. This disease is of special interest with the finding that CXCR4 antagonists can increase blood leukocytes and may be a therapeutic option for these patients. (Dale DC et al EHA abstract, Jun 16, 2018; McDermott DH et al., N Engl J Med 2019; 380: 163). Methods: Through the Severe Chronic Neutropenia International Registry (SCNIR) we identified 9 WHIM families in the US with 24 affected members: 13 female, 11 male, median age 31.9 years, mean 35.2 +/- 21.6 SEM (range 0.4 to 82), with mutations p.R334x (16), p.E343x (3), p.fs344x (3), or p.fs365x (2). As expected, family members had the same CXCR4 mutation. In these families, the diagnosis of WHIM syndrome usually followed from a patient seeing a physician because of recurrent fevers and infections and having a CBC revealing a very low WBC. Findings: We investigated the diversity of clinical manifestations and outcomes in these patients. Immunoglobulin levels were low but not extremely low, e.g., IgG mean of 683 mg/dL +/- 53.1, median 668 mg/dL, range 443-1188 mg/dL, and only 2 patients were treated with long-term IVIG treatment. There was no apparent difference in outcomes. Most patients have received routine vaccinations and appear to mount normal or near normal IgG responses to tetanus, rubella, rubeola and H. influenza type B, based on serial observations in 6 patients. By contrast, response to human papilloma virus vaccine in these same patients appeared to be much weaker and unsustained. Off all therapies and absent infection, profound leukopenia (WBC mean 1.83 x 109/L +/- 0.21, median 1.48 x 109/L, range 0.30 - 7.90 x 109/L, neutropenia mean 0.42 x 109/L +/- 0.08, median 0.21 x 109/L, range 0.00 - 6.48 x 109/L, lymphocytopenia mean 1.18 x 109/L +/- 0.20, median 0.84, range 0.04 - 4.14) was a consistent finding across ages and mutations. Fifteen patients received low dose G-CSF (median dose 1.56 mcg/kilogram/day) most intermittently but one patient was on G-CSF for 28 years. G-CSF elevated neutrophils but did not increase other leukocyte counts. Intermittent bacterial or presumed bacterial infections (otitis, sinusitis, pharyngitis, bronchitis, skin abscesses and cellulitis) were relatively common. Several patients were known to have hearing loss secondary to repeated episodes of otitis media. Serious infections requiring hospitalizations were rare, estimate at less than one per year. Warts were also quite variable within families living in the same household. There was no apparent genotype/phenotype association of warts but they did tend to accumulate with age and did not regress spontaneously. In this cohort, 4 patients developed malignancies: 1 AML (death age 12.3 years), 2 HPV-associated cervical cancer (death ages 46 and 73), and 1 lymphoma (death age 48). Cervical dysplasia is a frequent problem and concern. Conclusions: Leukopenia, neutropenia and lymphocytopenia are the most consistent features of WHIM syndrome. Hearing loss, disfiguring and disabling warts and HPV associated malignancies are its most serious complications. The variability of warts, respiratory and skin infections may be due to environmental factors. The promise of novel therapies should lead to more frequent diagnosis and early treatment to prevent the numerous serious complications of this syndrome. Disclosures Dale: Athelas: Equity Ownership; Amgen: Consultancy, Research Funding; Hospira: Consultancy; Prolong: Consultancy; Beheringer/Ingelheim: Consultancy; Cellerant: Other: Scientific Advisory Board; Coherus: Consultancy; x4pharma: Consultancy, Honoraria, Research Funding; Sanofi Aventis: Consultancy, Honoraria.

PF353 PATIENTS WITH SEVERE CHRONIC NEUTROPENIA SUBTYPES TREATED WITH BIOSIMILAR FILGRASTIM: A STUDY BY THE EUROPEAN BRANCH OF THE SEVERE CHRONIC NEUTROPENIA INTERNATIONAL REGISTRY

Background:Severe chronic neutropenia (SCN) is a group of very rare blood disorders, characterised by low levels of neutrophils (&lt;500/μl) lasting for extended periods of time, while other blood‐cell counts remain close to or within normal range. Since the introduction of granulocyte colony‐stimulating factor (G‐CSF) therapy in 1987, the prognosis and quality of life of patients with congenital neutropenia has vastly improved. The Severe Chronic Neutropenia International Registry (SCNIR), established in 1994, has gathered data on over 2,000 patients with SCN worldwide in order to monitor the clinical course, treatment and disease outcomes of patients with these rare diseases.Aims:This report by the European Branch of the SCNIR aims to compare results of patients with SCN treated with G‐CSF products (reference filgrastim, pegfilgrastim, lenograstim) with those who received Sandoz biosimilar filgrastim (Zarzio® or Filgrastim Hexal®) from July 2011 to March 2018.Methods:Since 1994, the European Branch of the SCNIR has been establishing a network including 26 European countries, Israel, Russia and Turkey. Clinical data on the course of neutropenia is collected after written informed consent by the patient or their legally authorised representative; all consent forms have been standardised and accepted by all local ethics committees.Results:Between 2011 and 2018, 789 patients were enrolled in the European registry, 578 (73.3%) of which had received G‐CSF. Of all G‐CSF treated patients (median age stable at approximately 14 years), the most common neutropenia diagnosis was congenital (n = 377), then cyclic (n = 88), idiopathic (n = 62), autoimmune (n = 30) and other (n = 21). Median G‐CSF dose was 3.01 μg/kg/day.Twenty‐one patients (median age 14.5 years; range 0.7–48.2 years) had received Sandoz biosimilar filgrastim (Zarzio®, n = 15; Filgrastim Hexal®, n = 6). Of the 21 patients, 16 had changed medication from other G‐CSF products. The most common diagnosis of neutropenia among these patients was congenital (n = 12) followed by cyclic (n = 6), idiopathic, autoimmune and other (n = 1 each). Median treatment duration was 1.5 (range, 0.1–4.4) years and median dose was 2.27 (range, 0.25–40) μg/kg/day. Absolute neutrophil counts (ANCs) during treatment indicated that all patients responded well to Sandoz biosimilar filgrastim. ANCs remained stable in the 16 patients who changed medication.Of the 578 patients who received G‐CSF, 50 have developed leukaemia secondary to SCN. Only one of these patients received Sandoz biosimilar filgrastim (Filgrastim Hexal® from March 2009 to November 2011); this patient suffered from congenital neutropenia and underwent successful stem cell transplant. So far, there have been no reports of osteoporosis, severe splenomegaly, splenic rupture, severe side effects or immunogenicity in any patient that received Sandoz biosimilar filgrastim.Summary/Conclusion:Efforts to register all patients with SCN within the co‐operating countries are ongoing, with the aim of estimating the incidence and prevalence of these rare disorders and the incidence of severe secondary events like leukaemia. G‐CSF remains the treatment of choice for patients with congenital neutropenia to maintain their ANC above 1,000/μL, which is required for the prevention of severe infections. With Sandoz biosimilar filgrastim, no new safety signals were observed and only one patient has developed leukaemia secondary to SCN during the observation period. In general, secondary leukaemia in congenital neutropenia patients is related to the underlying genetic disorder.

Extended Genetic Testing in Severe Congenital Neutropenia May Identify Mutations That Inform Therapy

The Severe Chronic Neutropenia International Registry (SCNIR) in cooperation with Washington University has developed a next-generation sequencing assay for the genetic diagnosis of chronic neutropenia. Exome-based sequencing is performed, and genetic alterations in 27 genes implicated in the pathogenesis of severe congenital neutropenia (SCN) are reported. Of note, with consent, patients are enrolled in the SCNIR to collect detailed clinical data and to allow researchers access to the exome sequence data to identify new genetic alterations contributing to disease pathogenesis, severity, and progression to acute myeloid leukemia. Here, we report sequencing results for 61 cases of SCN, 31 cases of cyclic neutropenia, and 3 cases of idiopathic or unclassified neutropenia. The median age of this cohort was 17.2 years (range 0.13 to 78 years). Ninety-eight per cent of the SCN cases received G-CSF with a median dose of 1.85 mg/kg/day (range, 0-99.3), and 87% of cyclic neutropenia cases received G-CSF with a median dose of 0.34 mg/kg/day (range, 0-5.2). ELANE mutation status was previously determined for the majority of these cases. In total, 16 of 95 cases of neutropenia had a known ELANE mutation, and the remainder of the cases had no genetic diagnosis.Initial analyses focused on the following genes previously implicated in SCN pathogenesis: ELANE, AP3B1, CSF3R, CXCR2, CXCR4, G6PC3, GFI1, HAX1, LYST, LAMTOR2, RAB27A, SBDS, SLC37A4, SRP54, TCIRG1, VPS13B, VPS45, USB1, TAZ, and WAS. Heterozygous mutations of ELANE were identified in the 16 previously identified cases, but in no additional cases. Of the remaining 50 cases of SCN, probable pathogenic mutations were identified in 8 (16%). Surprisingly, in the 27 cases of cyclic neutropenia with wildtype ELANE, no probable pathogenic mutations were identified. We identified three cases of SCN (including two family members) with biallelic mutations of G6PC3 and single cases of SCN with N382S GFI or R184C TCIRG1 mutations. A novel homozygous R547X CSF3R mutation was seen in one case of SCN. This truncation mutation in the extracellular domain of the G-CSF receptor is predicted to result in a complete loss-of-function allele. Indeed, this patient was refractory to G-CSF therapy. We also identified a single case of SCN carrying a R338X CXCR4 mutation, the cause of WHIM syndrome. Of note, emerging data suggest that the neutropenia in WHIM syndrome can be effectively treated with CXCR4 antagonists. We identified two cases of SCN carrying heterozygous mutations of SRP54, G175E and T191I, respectively. These SRP54 mutations, although not previously reported, localize to the GTPase domain of SRP54 (similar to previously identified SRP54 mutations), and they have not been identified in over 60,000 individuals in the ExAC database.Conclusions: Extended genetic testing in patients with chronic neutropenia and wildtype ELANE, although identifying a pathogenic mutation in the minority of cases, may impact the choice of therapy. Analyses of the exome sequence data are underway to identify novel candidate genes contributing to neutropenia. DisclosuresDale:Athelas, Inc.: Equity Ownership; Amgen: Consultancy, Research Funding; Sanofi-Aventi: Consultancy, Honoraria; Cellerant: Other: Scientific Advisory Board; Hospira: Consultancy; Prolong: Consultancy; Beheringer-Ingelheim: Consultancy; Coherus: Consultancy.

Myelodysplasia, Leukemia, Lymphoid Malignancies, and Other Cancers in Patients with Severe Chronic Neutropenia

Background: Since 1994 the Severe Chronic Neutropenia International Registry (SCNIR) has enrolled children and adults with > 3 absolute neutrophil counts (ANCs) < 0.5 x 109/L during a 3 month period to understand the pathobiology, natural history and treatment responses for severe chronic neutropenia. We have previously reported on the frequency and risk of myelodysplasia (MDS) and acute myeloid leukemia (AML) in patients with congenital neutropenia. For this report we reviewed patterns of hematological complications and malignancies occurring in all patients enrolled through the North American office of the SCNIR.Methods: Enrollment required informed consent, and patients and their physicians provided demographic, clinical and laboratory data including bone marrow results. Genetic testing was not required. Patients were followed with annual reports on blood counts, infections, malignancies and hospitalizations.Results: From 1994 to 2018 the Seattle SCNIR office has enrolled 1672 patients in the following categories: congenital 637 (38%), cyclic 259 (15%), and idiopathic / autoimmune 776 (47%), and many have been followed now for more than 15 years. There are approximately 17,577 person years of the observational data in this Registry. The congenital category now includes patients with mutations in ELANE, SBDS, TAZ, COH1, CXCR4, SLC37A4, G6PC3, WAS, CSF3R, SRP54, GFI1, VPS45, JAGN1, HAX1 and also patients with severe neutropenia from an early date in childhood without a genetic diagnosis. Cyclic neutropenia patients have demonstrated oscillations in ANC. The idiopathic and autoimmune category includes children and adults including some with large granular lymphocytes (LGL) syndrome without recognized features of a lymphoproliferative disorder. Most patients in all categories have been treated with granulocyte colony-stimulating factor (G-CSF).Findings: MDS or AML has occurred in 70 of the 1672 patients; 99% have clinical diagnosis of a hereditary type of neutropenia: severe congenital neutropenia (55), glycogen storage disease 1b (3), congenital immunodeficiency (2), Shwachman-Diamond syndrome (SDS) (5), WHIM syndrome (1),Wiskott-Aldrich syndrome (2), cyclic neutropenia (1) and idiopathic neutropenia (1). The median age at diagnosis of AML/MDS was 15.3 years (mean 18.3, +/- 1.79 SEM [range 0.40 - 70.6]); 69 of 70 were treated with G-CSF, median dose = 7.1 mcg/kg/day (mean 7.3, +/- 1.3 SEM )(range 0.18 - 100). One Shwachman-Diamond patient never received G-CSF. Outcomes for AML/MDS patients receiving chemotherapy with HSCT before 2000 were poor with 3/17 (18%) survivors. Since 2000 there were 35/53 (66%) survivors. Five patients developed myelofibrosis (4 congenital and 1 idiopathic). Two of the congenital patients later developed AML (1 living after treatment with a HSCT, 1 deceased). The clinical diagnosis of cyclic neutropenia has a favorable prognosis with G-CSF treatment, with only one probable case in 3,833 person years of clinical observation. 1Twelve patients developed T-cell lymphoproliferative disorder (1 autoimmune neutropenia, 3 congenital neutropenia, 8 idiopathic neutropenia (4 with LGL features)). Five of these patients are living, all in the idiopathic group, 3 of 5 living patients have features of the LGL syndrome.Ten patients have reported other hematological malignancies; CML in a congenital patient after treatment with HSCT (living), CLL in a cyclic patient (living), CMML in an idiopathic patient after treatment with a HSCT (deceased). Six of the 10 patients have developed lymphoma; cyclic neutropenia (1), idiopathic/autoimmune neutropenia (5). Only one SDS patient has developed aplastic anemia.Other cancers/non-hematological malignancies have occured mostly in older patients: breast cancer (15) colon cancer (6), dermatological malignancies (13), hepatoma (1), lung cancer (1), prostate cancer (1), thyroid cancer (1).Conclusions: The hematological consequences of severe chronic neutropenia depend on the underlying etiology. MDS and AML occur largely in patients with the congenital or hereditary neutropenias. The diagnosis of cyclic neutropenia and chronic idiopathic / autoimmune neutropenia portends a favorable prognosis, based on a total of 10482 person years of observation. Marrow failure and aplastic anemia are not expected consequences of severe chronic neutropenia. DisclosuresDale:Athelas, Inc.: Equity Ownership; Amgen: Consultancy, Research Funding; Sanofi-Aventi: Consultancy, Honoraria; Cellerant: Other: Scientific Advisory Board; Hospira: Consultancy; Prolong: Consultancy; Beheringer-Ingelheim: Consultancy; Coherus: Consultancy. Newburger:X4 Pharmaceutics: Consultancy, Honoraria; TransCytos LLC: Consultancy; Janssen Research & Development, LLC: Consultancy, Honoraria.

Editorial introductions

Current Opinion in Hematology was launched in 1994. It is part of a successful series of review journals whose unique format is designed to provide a systematic and critical assessment of the literature as presented in the many primary journals. The field of hematology is divided into nine sections that are reviewed once a year. Each section is assigned a Section Editor, a leading authority in the area, who identifies the most important topics at that time. Here we are pleased to introduce the Editor and the Section Editor for this issue. EDITOR Thomas P. StosselThomas P. StosselStossel graduated from Princeton University (summa cum laude) and Harvard Medical School (cum laude from). He trained in internal medicine, hematology and research at Boston's Massachusetts General and Children's Hospitals and at the National Institutes of Health (NIH). He served as professor of medicine at Harvard Medical School, head of hematology-oncology at the Massachusetts General Hospital and of experimental medicine and hematology at Brigham & Women's Hospital. He was President of the American Society for Clinical Investigation and of the American Society of Hematology, and served on the Lasker Awards Jury and as editor-in-chief of The Journal of Clinical Investigation. He is now editor in chief of Current Opinion in Hematology, on the editorial advisory board of Collabryx and the scientific advisory board of The Forsyth Dental Institute. The NIH continuously funded his research on mechanisms of how cells move about the body for over 40 years. This research won him an American Cancer Society Professorship and election to The National Academy of Sciences, The American Academy of Arts and Sciences, and The National Academy of Medicine. He also received honorary degrees from Linköping and Geneva Universities, an NIH MERIT award, and the Dameshek and Thomas Awards of the American Society of Hematology. He has authored 299 publications and two textbooks, and is an inventor on 17 issued patents. He was a scientific advisor to Biogen and Dyax Corporations and currently is a Director of Velico Corporation and Founding Scientist and Director of BioAegis Therapeutics, companies undertaking respectively clinical development of his discoveries concerning blood transfusion and inflammation control. For his policy work concerning the medicine-industry interface, he received the Academy of Pharmaceutical Physicians’ Sherwood and American Medical Writers Association's McGovern Awards and was appointed a Visiting Scholar of the American Enterprise Institute. Rowman and Littlefield published his book on this topic in 2015 (Pharmaphobia: How the Conflict of Interest Myth Undermines American Medical Innovation). With his wife, Kerry Maguire (DDS, MSPH and others), Stossel co-founded a 5013c charity, Options for Children in Zambia, that provides voluntary dental and medical care in that Sub-Saharan African country. For this effort he received the 2012 Humanitarian Award of the Brigham & Women's Hospital Hippocrates Society. SECTION EDITOR David C. DaleDavid C. DaleDr David C. Dale, Professor of Medicine at the University of Washington, USA, is a native of Knoxville, Tennessee, and a graduate of the Harvard Medical School, USA. He trained in Internal Medicine at Massachusetts General Hospital Boston, USA, and the University of Washington Medical Center, USA and received research training at the National Institutes of Health, National Institute of Allergy and Infectious Diseases, USA. His research interests are in inflammation, neutrophils, and the clinical problem of neutropenia, interests which link the specialties of hematology, oncology and infectious diseases. Dr Dale is actively involved in teaching, research and patient care at the University of Washington, where he served as dean of the school of medicine. He is a member of the American Society for Clinical Investigation, Association of American Physicians, American Clinical and Climatological Association, American Society of Hematology, Infectious Disease Society of America, and American Society for Clinical Oncology. He has served as President of the American College of Physicians (ACP) and chair of the Board of Governors. He also served as a member of the Board of Regents of ACP, President of the Society of General Internal Medicine, President of the Western Association of Physicians, President of the Medical Honor Society-Alpha Omega Alpha, and is currently President of the American Clinical and Climatological Association. He is editor-in-chief Emeritus of the medical textbook, Scientific American Medicine and has served on the National Board of Sponsors for Physicians for Social Responsibility. He is co-Director of the Severe Chronic Neutropenia International Registry.

Long-Term Outcomes for G-CSF Treatment of Patients with Glycogen-Storage Disease Type Ib

Background: Glycogen-storage disease 1b (GSD 1b) is characterized by neutropenia, hepatomegaly, hypoglycemia, enterocolitis and recurrent severe infections. For more than 25 years, many GSD 1b patients worldwide have been treated with granulocyte colony-stimulating factor (G-CSF).Methods: The Severe Chronic Neutropenia International Registry (SCNIR) enrolls and prospectively follows GSD 1b patients with both severe (ANC< 0.5 x 109/L) and mild or moderate neutropenia (ANC< 1.5 x 109/L). For this report we analyzed records for 83 patients enrolled through the SCNIR offices in Seattle, Washington and Hannover, Germany.Findings -Clinical outcomes: Overall most patients and parents report very favorable outcomes with increases in neutrophils, reduced infections, reduced symptoms of enterocolitis and improved quality of life.Neutropenia: Because splenomegaly may increase markedly with G-CSF treatment, clinical experience dictates that the G-CSF dose should be carefully monitored to maintain the ANC at 1.0 to 2.0 x 109/L. Summary data for treatment of 83 patients are shown in Table 1.Myeloid malignancies: We assessed the risk of GSD 1b patients developing myeloid malignancies from review of the medical literature and patients prospectively followed through the SCNIR. We identified 1 case of AML prior to availability of G-CSF and 6 cases of AML in G-CSF treated patients, 4 from the cohort followed prospectively by the SCNIR. Table 2 shows detailed data for the 7 patients with GSD1b who have developed AML.Conclusions: In the 83 SCNIR patients followed for a mean (median) of 12.2 (11.0) years there are 4 cases (4/83, 4.8%) of AML, or 1 case/253 years of G-CSF treatment. This is lower than the estimated risk of evolution to AML in the major genetic subgroups of severe congenital neutropenia treated with G-CSF, e.g., harboring ELANE, HAX1, SDS mutations . The numbers of patients in other genetic subgroups, such as G6PC3, JAGN1, TCIRG1, etc. are too small to make any reliable comparison about the risk of developing leukemia. (Skokowa J et al. Nat Rev Dis Primers. 2017 Jun 8. doi: 10.1038/nrdp.2017.32. [Epub ahead of print]). [Display omitted] DisclosuresDale:Amgen: Consultancy, Research Funding; Sanofi Aventis: Consultancy, Editor, Current Opinions in Hematology, Honoraria; Cellerant: Membership on an entity's Board of Directors or advisory committees; Genzyme (now owned by Sanofi-Aventis): Consultancy, Patents & Royalties, Research Funding; Genkyotex: Other: DSMB (work completed 6/2015); Hospira: Consultancy; Prolong: Consultancy; Boheringer-Ingelheim: Consultancy; Coherus: Consultancy; Omeros: Other: DSMB; Shire: Other: Independent Review Board; X4Pharma: Research Funding; Philips: Research Funding; Wolter Kluwer: Other: Editor, Current Opinions in Hematology; WedMD/Medscape: Membership on an entity's Board of Directors or advisory committees; National Institutes of Health: Research Funding; University of Washington: Employment, Research Funding; American College of Physicians: Other: Editor and author; GlaxoSmithKline: Equity Ownership; Johnson&Johnson: Equity Ownership. Weinstein:Vitaflo: Research Funding; Dimension Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Peg-Filgrastim for the Treatment of Severe Chronic Neutropenia

Background: Peg-filgrastim (peg-G) is widely used in oncology to accelerate hematopoietic recovery after cancer chemotherapy. It is used occasionally for the treatment of severe chronic neutropenia (SCN). Because of frequent questions from clinicians, we reviewed the use of peg-G, its effectiveness and associated adverse effects for SCN patients followed prospectively through the Seattle office of the Severe Chronic Neutropenia International Registry (SCNIR).Methods: The SCNIR is a long-term observational study of children and adults with congenital, cyclic, idiopathic and autoimmune neutropenia. They are enrolled according to a protocol requiring a minimum of 3 absolute neutrophil counts (ANCs) <0.5 x 109/L over at least a 3 month period. Patients are treated according to the practices of individual physicians; treatments are not prescribed by the study protocol or the SCNIR. Patients and their physicians regularly report treatments for neutropenia including drug doses, schedules, blood counts, infections and associated adverse events. SCNIR-Seattle includes patients in North and South America and Australia. Patients are followed through annual report forms and notes whenever serious illness or adverse events occur.Results: Peg-G has been administered to 37 of 1571 patients enrolled in the SCNIR-Seattle: 12 children (age <18 years) and 25 adults (age >18 years). Common reasons for peg-G treatment were: convenience, patient dislike of injections, or poor response to filgrastim. Table 1 summarizes peg-G exposures:All of the patients responded to peg-G with an increase in ANC over their baselines, but detailed pharmacodynamics to show the patterns of the rise and fall of the counts were not available. As shown in Table 1, the duration of treatment was relatively short for three groups: idiopathic, autoimmune and cyclic patients. In these patients, bone pain is a common adverse effect of the fixed doses of peg-G usually administered. Sweet syndrome was reported for only 1 patient with idiopathic neutropenia.The majority of the reported use of peg-G is for patients with congenital neutropenia who are relatively refractory to G-CSF; 4 of 9 peg-G treated congenital neutropenia patients had been previously treated with G-CSF >10 mcg/kg/day. In the congenital subgroup, adverse events included splenomegaly (8), hepatomegaly (4) and AML (2). Following are brief descriptions of the cases of MDS/AML:Patient #1: A 38 year old female initially diagnosed with SCN in 1989 at age 11 (ELANE mutation C223ter) and started G-CSF at 11.5 mcg/kilograms per day. Because of a poor response, G-CSF was increased to 24 mcg/kg/day. After 15 years she was switched to peg-G (3mg/injection) approximately every 10 days for the next 11 years. At age 37 she had increased blasts in the blood and marrow, leading to the diagnosis of AML and HSCT.Patient #2: A 25 year old female (unrelated to patient #1) was initially diagnosed with SCN at 4.5 months of age (also ELANE mutation C223ter). At age 5 months she started G-CSF (5 mcg/kg/day increased soon to 20 mcg/kg/day). After 12 years, she was switched to peg-G (6 mg/injection) because of poor neutrophil response, and she received peg-G every 14 days for the next 12 years. She became pregnant (previously 3 pregnancies: 2 terminations and one live birth). Early in the pregnancy she appeared to be losing her response to peg-G. Her gums were infiltrated by immature myeloid cells and there were excess blasts in her bone marrow leading to the diagnosis of AML. With intensive care, she delivered a male infant at 30 weeks via C-section and then underwent an HSCT five weeks thereafter.Conclusions: Patients with severe chronic neutropenia respond to treatment with peg-G but it is not easy to determine the proper dose and dosing interval. Bone pain is a common early adverse effect and Sweet syndrome may occur. In patients with congenital neutropenia who are refractory to G-CSF prolonged responses have been achieved lasting for many years with regular injections of peg-G at approximately 14 day intervals. However, 2/9 refractory congenital neutropenia patients developed AML after 11 and 12 years, respectively. Based on this experience, we recommend that peg-G should only be used in congenital neutropenia patients who are refractory to G-CSF (>20 mcg/kg/day) while searching for a donor for HSCT. [Display omitted] DisclosuresBoxer:Amgen: Equity Ownership. Dale:Amgen: Consultancy, Honoraria, Research Funding.

TCIRG1 Mutations As a Cause for Chronic Neutropenia

Background: Heterozygous mutations in TCIRG1 are recently associated with congenital neutropenia. [Makaryan et al, Human Mutation, 2014] Recent large scale population study revealed statistically significant association between absolute neutrophil count and variations in TCIRG1 gene. [Rosenthal et al, Genetic Epidemiology, 2016]Aims: To investigate frequency and reveal possible asymptomatic cases of TCIRG1 associated neutropenia.Methods: The Severe Chronic Neutropenia International Registry (SCNIR) enrolled and followed 2 multigenerational families with genetic neutropenia of unknown etiology with a clear autosome dominant inheritance. Exome sequencing of selected affected members from these families revealed two previously reported heterozygous single point mutations in TCIRG1. Confirmatory Sanger sequencing ratifies exome sequencing results.Results:Family 1: P161L (c.482C>T) single point substitution detected in 3 members of this family. This variant is very rare in population and has relatively low minor allele frequency (MAF) score: 0.08. Proline residue at this position is highly conserved and has a high genomic evolutionary rate profiling (GERP) score: 3.46. PolyPhen-2 analysis suggests this substitution as possibly damaging.Family 2: I721N (c.2162T>A) single point substitution detected in 3 members of this family. This variant is also very rare in population and has MAF score: 0.07. Isoleucine at this position is relatively conserved and has GERP score: 2.73. PolyPhen-2 analysis suggests this substitution as probably damaging.Summary/Conclusion: Understanding the genetic, epidemiological and biological basis of TCIRG1 associated neutropenia is critical for improving the diagnosis and treatment of this form of hereditary neutropenia. The pathological mechanisms for TCIRG1-associated neutropenia are not yet known. In our original report [Makaryan et al, Human Mutation, 2014] of the large family with TCIRG1-associated neutropenia, all carriers of the pathogenic variant had neutropenia, with variable severity. Some members have severe neutropenia and associated infections whereas others are mildly affected. The report of these two new variants in these families suggests that there may be other patients and families with neutropenia caused by variants in TCIRG1. DisclosuresDale:Amgen: Consultancy, Honoraria, Research Funding.